Serum metabolites, milk yield, and physiological responses during the first week after kidding in Anglo-Nubian, Angora, Baladi, and Damascus goats under subtropical conditions

Abstract

This study was carried out to determine the level of certain biochemical variables reflecting the energy metabolic statuses during the first week of lactation in goats. A total of 120 Anglo-Nubian, Angora, Baladi, and Damascus does (30 does per breed) were used throughout 5 consecutive parities (30 does per parity) to investigate the effect of breed, parity, day of lactation, and their interaction on serum metabolites including total protein, albumin, globulin, glucose, total lipids, cholesterol, and transaminases. Blood samples were collected every other day during the first week of lactation. Baladi does had the greatest (P < 0.001) values in all measured biochemical variables followed by Anglo-Nubian [in total protein, globulin, and aminotransferase (AST)] and Damascus (in globulin and AST) and then Angora, which had the lowest (P < 0.001) values for all variables. Fifth parity exhibited the greatest (P < 0.001) values in all serum metabolites compared with other parities except for alanine transaminase (ALT) enzyme activity in which the greatest (P = 0.046) values were observed in the first and fourth parties. Serum concentrations of the measured variables increased gradually throughout the first day after kidding until the seventh day for total protein (P < 0.001), albumin (P = 0.013), globulin (P = 0.017), and cholesterol (P = 0.028) whereas serum glucose concentration exhibited an opposite trend. Serum concentrations of total lipids and enzyme activities of AST and ALT were not affected by day (P > 0.05) after kidding. Baladi goats had the least (P < 0.001) serum insulin concentration, which was associated (P < 0.001) with greatest serum glucose concentration. Serum triiodothyronine (T(3)) was inversely correlated (P = 0.032) with milk yield whereas greatest (P = 0.003) T(3) concentrations were associated with least (P < 0.001) milk yield recorded in Angora goats. Animal physiological responses and their indices were not affected (P > 0.05) by breed whereas both rectal temperature and coefficient of heat tolerance were affected (P < 0.001) by parity in an opposite direction. Baladi goats expressed an aspect of adaptability where their rectal temperature decreased and coefficient of heat tolerance increased with increasing parity number.